This invention relates to a lateral pipe adaptor, more particularly for connecting into a structured wall plastic pipe a lateral pipe of smaller diameter.
Structured wall plastic pipes are used widely for drainage applications throughout Europe and are manufactured from 100 mm bore to 1050 mm and above. These pipes can be made from a range of plastic materials, such as polyethylene or polypropylene depending on the manufacturer. They are formed in a two-layer construction. The inner layer provides a smooth surface for the bore of the pipe. The outer layer is of corrugated construction that creates ribs around the circumference of the pipe, these ribs being equispaced along the length of the pipe. The ribs are also hollow. Their purpose is to provide structural strength in the pipe wall.
It is often necessary to connect into these pipes, smaller lateral pipes from gullies or other such drainage points. Normal practice with these pipe systems is to use a purpose made branch fitting. Due to the popularity of using lateral adaptors to make connections into rigid pipe systems, e.g. concrete or clay, there is a demand for a similar solution for flexible pipes (plastic).
The lateral pipe will commonly be of around 150 mm bore and often of similar construction to the main pipe, in this case structured wall plastic. Other materials such as clay or solid wall plastic will also be used in some circumstances. The method of access into the pipe is by the use of a holesaw that leaves a fairly untidy cut surface that cannot be reasonably or easily made good on site. It is a requirement that any lateral adaptor will overcome this and create and maintain a leaktight connection that prevents leakage from the pipe and ingress of groundwater.
The object of the invention is to provide a lateral pipe adaptor that is easy to install in a main pipe with a hole cut with a holesaw to provide a means of connecting lateral pipes of any material by means of a proprietary pipe adaptor between the spigot of the lateral pipe adaptor and the incoming lateral pipe.
According to the present invention, a lateral pipe adaptor for a main pipe, such as a structured wall plastics pipe, comprises a cylindrical sleeve with a flange extending outwardly at one end and curved to match the internal curvature of the main pipe and adapted at the other end for connection of a branch pipe (e.g. by provision of a spigot or socket), an annular movable member slidable on the sleeve and having a curved face to match the external curvature of the main pipe, an elastomeric seal ring held captive between the flange of the sleeve and the movable member and having inner and outer curved faces to match the curvature of the flange on the sleeve and the movable member respectively, an annular abutment member adjacent the face of the movable member remote from its curved face, at least one projection on the sleeve (e.g. an annular shoulder) abutted by the face of the abutment member remote from the movable member, and loading means for urging the movable member away from the abutment member to compress the seal ring axially after passing of the flange of the sleeve through a hole in the main pipe to bring the seal ring within the hole, the axial compression of the seal ring causing radial expansion of the seal ring into sealing engagement with all parts of the hole in the main pipe and all round the sleeve. A socket provided for the connection of a branch pipe may be an interchangeable component attached to the sleeve.
The seal ring preferably has an axial length appreciably in excess of the depth of the hole in the main pipe, to ensure that when axially compressed in a hole in a structured wall plastics pipe all the edges within the hole are sealingly contacted by the seal ring.
The sleeve preferably has an increasing outer diameter adjacent its flange, to promote radial expansion of the seal ring from its face adjacent the flange, particularly to ensure sealing contact all round the inner edge of the hole in a structured wall plastics pipe.
The sleeve and the movable and abutment members may be conveniently moulded in plastics, and the movable member is provided with a curved flange (or xe2x80x9csaddlexe2x80x9d) providing the curved face matching the outer curvature of the main pipe co-moulded with a thin cylindrical wall having bosses with shallow recesses for location of axial screws projecting from lugs on the abutment member, and the lugs of the latter being provided with non-circular recesses to accommodate non-rotatable nuts for the axial screws.
For convenience of manufacture and assembly, the movable member is preferably formed in two identical parts, split on a diametral line and each provided with at least one projection and one recess for engagement with the recess and projection, respectively, of the other upon fitting of the parts round the sleeve.
Likewise, the abutment member is preferably formed with a split at one side only and provided with overlapping bosses having respectively a projection and a recess for engagement with each other after fitting the abutment member round the sleeve in abutting engagement with the projection (e.g. annular shoulder) on the sleeve.